1. Field of the Invention
This invention relates generally to vascular interventional medical devices, and more particularly concerns guide wires for use in a therapeutic system or for delivery of medical devices.
2. Description of Related Art
Conventional minimally invasive catheter based therapies typically require guidewires that are one to two meters long extending through a longitudinal lumen in the catheter, and that are torqueable and pushable at the proximal end, yet soft and flexible at the distal end. Many such guidewires are made of stainless steel or the like, and are ground to tapers which provide the desired bending properties along the guidewire. It is useful for such guidewires to be torqueable from the base of the guidewire for manipulation of the distal tip, which is typically bent, for guiding the distal tip through vascular passages. While such guidewires need to be torqueable, pushable and resilient, particularly at the proximal regions of the guidewire, they also need to be flexible, particularly at the distal regions of the guidewire.
One prior guidewire for use with a catheter includes a core wire formed from a nickel titanium alloy, with a tapered distal tip portion and a distal end cap, covered by a sheath of material such as polyurethane, polyethylene, nylon, silicone, polytetrafluoroethylene, cellulose, starch or gelatin. Another prior guidewire comprises a composite guidewire with a core of stainless steel or a nickel titanium alloy, a tapered distal region ending in a distal flexible coil and end cap, also having a major portion of the guidewire covered by a thin layer of polymeric material, such as polysulfones, polyfluorocarbons, polyolefins, polyesters, polyamides, polyurethanes, blends and copolymers such as polyether block amides.
However, there remains a need for a guidewire with enhanced proximal stiffness, with a stiff, high modulus reinforcement, allowing for greater manipulation of the guidewire by the physician, along with greater distal tip flexibility with radiopacity. The present invention meets these needs.